Effective Objective-C 2.0

Acknowledgments xv

About the Author xvii

Chapter 1: Accustoming Yourself to Objective-C 1

Item 1: Familiarize Yourself with Objective-C's Roots 1

Item 2: Minimize Importing Headers in Headers 4

Item 3: Prefer Literal Syntax over the Equivalent Methods 8

Item 4: Prefer Typed Constants to Preprocessor #define 12

Item 5: Use Enumerations for States, Options, and Status Codes 17

Chapter 2: Objects, Messaging, and the Runtime 25

Item 6: Understand Properties 25

Item 7: Access Instance Variables Primarily Directly When Accessing Them Internally 33

Item 8: Understand Object Equality 36

Item 9: Use the Class Cluster Pattern to Hide Implementation Detail 42

Item 10: Use Associated Objects to Attach Custom Data to Existing Classes 47

Item 11: Understand the Role of objc_msgSend 50

Item 12: Understand Message Forwarding 54

Item 13: Consider Method Swizzling to Debug Opaque Methods 62

Item 14: Understand What a Class Object Is 66

Chapter 3: Interface and API Design 73

Item 15: Use Prefix Names to Avoid Namespace Clashes 73

Item 16: Have a Designated Initializer 78

Item 17: Implement the description Method 84

Item 18: Prefer Immutable Objects 89

Item 19: Use Clear and Consistent Naming 95

Item 20: Prefix Private Method Names 102

Item 21: Understand the Objective-C Error Model 104

Item 22: Understand the NSCopying Protocol 109

Chapter 4: Protocols and Categories 115

Item 23: Use Delegate and Data Source Protocols for Interobject Communication 115

Item 24: Use Categories to Break Class Implementations into Manageable Segments 123

Item 25: Always Prefix Category Names on Third-Party Classes 127

Item 26: Avoid Properties in Categories 130

Item 27: Use the Class-Continuation Category to Hide Implementation Detail 133

Item 28: Use a Protocol to Provide Anonymous Objects 140

Chapter 5: Memory Management 145

Item 29: Understand Reference Counting 145

Item 30: Use ARC to Make Reference Counting Easier 153

Item 31: Release References and Clean Up Observation State Only in dealloc 162

Item 32: Beware of Memory Management with Exception-Safe Code 165

Item 33: Use Weak References to Avoid Retain Cycles 168

Item 34: Use Autorelease Pool Blocks to Reduce High-Memory Waterline 173

Item 35: Use Zombies to Help Debug Memory-Management Problems 177

Item 36: Avoid Using retainCount 183

Chapter 6: Blocks and Grand Central Dispatch 187

Item 37: Understand Blocks 188

Item 38: Create typedefs for Common Block Types 194

Item 39: Use Handler Blocks to Reduce Code Separation 197

Item 40: Avoid Retain Cycles Introduced by Blocks Referencing the Object Owning Them 203

Item 41: Prefer Dispatch Queues to Locks for Synchronization 208

Item 42: Prefer GCD to performSelector and Friends 213

Item 43: Know When to Use GCD and When to Use Operation Queues 217

Item 44: Use Dispatch Groups to Take Advantage of Platform Scaling 220

Item 45: Use dispatch_once for Thread-Safe Single-Time Code Execution 225

Item 46: Avoid dispatch_get_current_queue 226

Chapter 7: The System Frameworks 233

Item 47: Familiarize Yourself with the System Frameworks 233

Item 48: Prefer Block Enumeration to for Loops 236

Item 49: Use Toll-Free Bridging for Collections with Custom Memory-Management Semantics 243

Item 50: Use NSCache Instead of NSDictionary for Caches 248

Item 51: Keep initialize and load Implementations Lean 252

Item 52: Remember that NSTimer Retains Its Target 258

Index 265